Random fading to provide a "stone-washed" or worn appearance is a highly popular fabric treatment in the clothing industry, particularly for denim fabric. Such fading is generally accomplished by means of bleaching the denim fabric, abrading the fabric by natural stones such as pumice, or bleaching the fabric in addition to fabric abrasion. The bleaching agent may be contacted to the fabric by either aqueous washing methods or by dry tumbling methods.
In the past, this worn appearance was provided merely by washing denim with pumice stone. Pumice, or lava rock, is porous and tends to abrade the fabric upon contact. Pumice and other similar natural rocks used in random fading processes break apart and tend to form sharp pieces which may tear garments or cause damage to the interior surface of processing equipment. Further, pumice, as it deteriorates during processing, forms sand and small rock pieces which are not easily separable from the treated garments. Typically, in garments treated by pumice, sand remains in the seams, pockets and other closed areas. In dryer tumbling methods using pumice, the drying chamber requires holes to remove the sand and broken rock pieces. Sand in the garment is a highly undesirable by-product of a pumice-based process as it acts as a skin irritant for a significant number of people wearing the treated fabric.
Subsequently developed methods, such as that of U.S. Pat. No. 4,720,213 for treating denim with abrasive stones impregnated with bleaching agents, provide an enhanced worn appearance over merely washing the fabric with abrasive stones. However, these processes retain the same disadvantages of other stone processes, including unwanted sand and fabric damage.
As a result of the disadvantages of using pumice stone, the clothing industry has attempted to develop a process which can economically achieve a similar or improved worn, randomly faded appearance such as that derived from existing pumice stone methods, but which does not create unwanted sand or damage the fabric.